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quantum mechanics

In the 1920s the Austrian physicist Erwin Schrödinger came up with what has become the central equation of quantum mechanics. It tells you all there is to know about a quantum physical system and it also predicts famous quantum weirdnesses such as superposition and quantum entanglement. In this, the first article of a three-part series, we introduce Schrödinger's equation and put it in its historical context.

The holy grail for 21st century physics is to produce a unified theory of everything that can describe the world at every level, from the tiniest particles to the largest galaxies. Currently the strongest contender for such a theory is something called M-theory. So what is this supposed mother of all theories all about?

Plants are amazingly good at something that is still flummoxing
us humans in our quest for sustainable energy sources: turning sunlight
into energy in an efficient way. Around 100 bilions tons of biomass
are produced annually through photosynthesis. The question is, how
exacty do plants do it?

Most of us think that we have the capacity to act freely. Our sense of morality, our legal system, our whole culture is based on the idea that there is such a thing as free will. It's embarrassing then that classical physics seems to tell a different story. And what does quantum theory have to say about free will?

Researchers in Germany have created a rare example
of a weird phenomenon predicted by quantum mechanics:
quantum entanglement, or as Einstein called it, "spooky action at a
distance". The idea, loosely speaking, is that particles which have
once interacted physically remain linked to each other even when they're
moved apart and seem to affect each other instantaneously.

According to Einstein, the past, present and future have exactly the same character - so why do we feel that there is a particular moment we call "now"? The physicist George Ellis looks for an answer in the curious laws of quantum mechanics.

Physicists at the University of California, Los Angeles set out to design a better transistor and ended up with a discovery that may lead to a new explanation of electron spin and possibly even the nature of space.

Quantum mechanics is usually associated with weird and counterintuitve phenomena we can't observe in real life. But it turns out that quantum processes can occur in living organisms, too, and with very concrete consequences. Some species of birds use quantum mechanics to navigate. And as Plus found out at a recent conference, studying these little creatures' quantum compass may help us achieve the holy grail of computer science: building a quantum computer.

The words quantum physics are usually associated with the weirder end of physics, including strange phenomena like superposition or quantum entanglement, the "spooky action at a distance" as Einstein called it. But it turns out that quantum mechanical processes occur in living systems too. Some species of birds use quantum mechanics to navigate and studying how they do it might actually help us with building quantum computers.

Quantum physics is a funny thing. With counterintuitive ideas such as superposition and entanglement, it doesn't seem to resemble reality as we know it, yet quantum physics is an incredibly successful theory of how the physical world operates. Plus attended the conference Quantum Physics and the Nature of Realtiy at the University of Oxford in September 2010. We spoke to Andrew Briggs, John Polkinghorne, Nicolas Gisin, David Wallace, Roger Penrose and Andrea Morello about how we can resolve the mysteries of quantum physics with our experience of reality. And we find out why quantum physics is just like riding a bike...